Rolling stairway

Abstract

A rolling platform ladder includes a frame supporting a stairway and a flat work platform area at the top of the stairway. The frame includes a base portion that has a cantilevered front area for preventing tipping over if the platform is overloaded. A main structural support column is placed at the center portion of the platform and extends down at an angle toward the rear of the base. At least a portion of the platform is positioned in front of the column during use. This configuration enables at least a portion of the platform to be positioned over machines, conveyors and over obstructions. A portion of the base extends in front of the frame so that it can extend under objects elevated slightly above a work surface such as an elevated conveyor or machine.

What is claimed as invention is: 
     
       1. A rolling stairway apparatus comprising: a) a frame having upper and lower end portions and a stairway extending between the upper and lower end portions, the stairway having a first tread at said lower end portion defining an entry to the stairway and a final tread at the upper end portion and a plurality of treads between the first and the final tread;   b) a platform supported upon the frame at the upper end portion and above the final tread that includes a flat surface that provides footing and a work area for a user that is substantially larger in area than the treads, the platform having a front edge portion and a rear edge portion, the front edge portion defining a frontal plane of the apparatus that limits placement of the platform against a vertical surface that extends as high as the platform;   c) the lower end portion of the frame including a wheeled base that includes a plurality casters that includes at least a first pair of casters positioned generally under the front edge portion of the platform and a second pair of the casters being positioned under the entry;   d) the frame providing structural support for holding the platform and stairway in elevated position and being configured to provide an open area below at least a portion of the platform and above the base so that objects can penetrate the frontal plane and occupy the area under the platform during use; and   e) the base including a pair of spaced apart outrigger portions extending in front of the frame with a space therebetween, said outrigger portions having respective free ends that are positioned at the frontal plane, said first pair of casters being outrigger wheels positioned at the free ends of the outrigger portions respectively.   
     
     
       2. The rolling stairway apparatus of claim 1 wherein the frame includes a plurality of diagonally extending stairway stringers. 
     
     
       3. The rolling stairway apparatus of claim 1 wherein the outrigger portion carries a pair of outrigger wheels that are smaller than the casters. 
     
     
       4. A rolling stairway apparatus comprising: a) a frame having upper and lower end portions and a stairway extending between the upper and lower end portions, the stairway having a first tread at said lower end portion defining an entry to the stairway and a final tread at the upper end portion and a plurality of treads between the first and the final tread;   b) a platform supported upon the frame at the upper end portion that includes a flat surface that provides footing and a work area for a user, the platform having a front edge portion and a rear end portion, the front edge portion defining a frontal plane of the apparatus that limits placement of the platform against a vertical surface that extends as high as the platform;   c) the lower end portion of the frame including a wheeled base that includes two pairs of casters, a first pair of the pairs of casters positioned generally under the platform and a second pair of the casters being positioned under the entry;   d) the frame providing structural support for holding the platform and stairway in elevated position and being configured to provide an open area below at least a portion of the platform and above the base so that objects can penetrate the frontal plane and occupy the area under the platform during use;   e) wherein the frame includes a pair of columns that connect to the base at the first pair of casters, each column being connected to a middle of the platform.   
     
     
       5. The rolling stairway of claim 4 wherein the frame comprises: a) a base having a pair of longitudinally extending, generally parallel beams;   b) a plurality of diagonally extending stairway stringers extending from the base and forming an acute angle with the base;   c) a platform having front and rear edge portions, the rear edge portion being affixed to the top end of the stringers; and   d) a column attaching to the platform at a position between the front and rear edge portions, the column attaching to the base at a position that is generally vertically aligned with the rear edge portion of the platform.   
     
     
       6. The rolling stairway apparatus of claim 5 wherein the base is at least twice as long between the stringers and the column as the length of the platform between the column and the stringers. 
     
     
       7. A rolling stairway apparatus comprising: a) a frame having upper and lower end portions and a stairway extending between the upper and lower end portions, the stairway having a first tread at said lower end portion defining an entry to the stairway and a final tread at the upper end portion and a plurality of treads between the first and the final tread;   b) a platform supported upon the frame at the upper end portion that includes a flat surface that provides footing and a work area for a user, the platform having a front edge portion and a rear edge portion, the front edge portion defining a frontal plane of the apparatus that limits placement of the platform against a vertical surface that extends as high as the platform;   c) the lower end portion of the frame including a wheeled base that includes two pairs of casters, one of the pairs of casters positioned generally under the platform and the other pair of the casters being positioned under the entry;   d) the frame including a column that extends from the middle of the platform to the base adjacent one of the pair of casters, and forming an acute angle with the frontal plane;   e) the frame providing structural support for holding the platform and stairway in elevated position and being configured to provide an open area below at least a portion of the platform and above the base and in front of the column.   
     
     
       8. A rolling stairway apparatus comprising: a) a frame having upper and lower end portions and a stairway extending between the upper and lower end portions, the stairway having a first tread at said lower end portion defining an entry to the stairway and a final tread at the upper end portion and a plurality of treads between the first and the final tread;   b) a platform supported upon the frame at the upper end portion that includes a flat surface that provides footing and a work area for a user, the platform having a front edge portion and a rear edge portion, the front edge portion defining a frontal plane of the apparatus that limits placement of the platform against a vertical surface that extends as high as the platform;   c) the lower end portion of the frame including a wheeled base that includes two pairs of casters, a first pair of the pairs of casters positioned generally under the platform and a second pair of the casters being positioned under the entry;   d) the frame providing structural support for holding the platform and stairway in elevated position and being configured to provide an open area below at least a portion of the platform and above the base so that objects can penetrate the frontal plane and occupy the area under the platform during use,   e) wherein the base includes an outrigger portion that extends in front of the first pair of casters;   f) wherein outrigger portion has outrigger wheels and the casters are of a first, uniform diameter, and the outrigger wheels are of a second, smaller diameter.   
     
     
       9. A rolling stairway apparatus comprising: a) a frame having upper and lower end portions and a stairway extending between the upper and lower end portions, the stairway having a first tread at said lower end portion defining an entry to the stairway and a final tread at the upper end portion and a plurality of treads between the first and the final tread;   b) a platform supported upon the frame at the upper end portion and above the final tread that includes a flat surface that provides footing and a work area for a user that is substantially larger in area than the treads, the platform having a front edge portion and a rear edge portion, the front edge portion defining a frontal plane of the apparatus that limits placement of the platform against a vertical surface that extends as high as the platform;   c) the lower end portion of the frame including a wheeled base that includes plurality of casters;   d) the frame providing structural support for holding the platform and stairway in elevated position and being configured to provide an open area below at least a portion of the platform and above the base so that objects can penetrate the frontal plane and occupy the area under the platform during use;   e) wherein the base includes a pair of outrigger portions that each extend in front of the frame, the outrigger portions having a space therebetween so that vertically extending objects can fit within said space when a user is working on the platform positioned above said space; and   f) the outrigger portions each having free end portions for engaging the underlying ground to prevent tipping of the apparatus, said free end portions being positioned adjacent said frontal plane, under the front edge portion of the platform.